Apparatus and method for data communication

ABSTRACT

An electronically controlled compression ignition engine is connected with an advanced cruise control system. The advanced cruise control system is capable of measuring distance to a vehicle or other object in front of equipment that is power by the compression ignition engine. Signals produced by the advanced cruise control system, at least in part, are used to determine the power output of the engine. In the event that the electronically controlled engine receives no signals from the advanced cruise control system, the electronic control may disengage or disable the advanced cruise control.

TECHNICAL FIELD

[0001] The present invention relates generally to the field ofon-highway trucks and more particularly to a data communication link foruse with electronically controlled on-highway truck engines.

BACKGROUND

[0002] In the past, many on-highway trucks used mechanically controlledengines, which had mechanical governors and were mechanically connectedwith a throttle input. While these engines worked well, there werelimitations in the variety of ways that the engine could be controlled.For example, timing and duration of fuel injection was typicallycontrolled by the physical configuration of a cam shaft and the specificfuel injectors used on the engine. The timing and duration of fuelinjection could be changed, but generally this required changing themechanical components of the engine, such as a fuel injector or thecamshaft. Electronically controlled engines greatly increased theflexibility of the fuel injection control for such engines. Using anelectronically controlled fuel injector such as a HEUI fuel injectormanufactured by the assignee of the present application, the controllercan vary the timing and duration of fuel injected into the individualcylinders without changing the mechanical configuration of the engine.This permits the control system to vary timing and duration fordifferent objectives, even while the engine is operating. For example, acontrol strategy could be developed to improve fuel economy whilemaintaining or improving emissions.

[0003] Other advantages of electronically controlled engines readilybecame apparent. Because the electronic control module could receiveinputs from sensors and, to some extent, send signals to actuators onthe vehicle and transmission, the engine's performance and operatingcharacteristics could be adjusted based on sensed vehicle ortransmission conditions. Many issued patents show examples of suchintegration. For example, U.S. Pat. No. 4,914,597, varies the enginepower output based on whether cruise control is engaged or not. Anotherexample is U.S. Pat. No. 4,493,303, issued to Mack Trucks Inc., variesthe engine power output based on the transmission gear that is currentlybeing used—the control allows the engine to produce greater power whenthe transmission is in one of the top two gears.

[0004] Still another example of the ability of electronically controlledengines to use signals from other systems is the use of distance sensingdevices to influence the operations of the engine's cruise controlsystem. As is known to those skilled in the art, conventional cruisecontrol systems use various operator inputs to store a target cruisecontrol vehicle speed, which is then typically used by the enginecontroller, along with other signals including vehicle speed, tocalculate and generate a fuel command to minimize the error between thetarget cruise control vehicle speed and the actual vehicle speed. Inthis manner, the cruise control system controls the engine speed tomaintain or control vehicle speed to the target speed. Advanced cruisecontrol systems add additional capabilities to the conventional cruisecontrol system. Typically an advanced cruise control system utilizes anelectromagnetic beam, such as a laser beam, a microwave radar beam, or avideo image, to determine the inter-vehicle distance and closure ratebetween the host vehicle and one or more forward vehicles. Thisinformation may then be used by the engine controller to automaticallyadapt to the traffic flow and “track” or follow the forward vehicle at adesired following distance selected by the operator. Distance andclosure rate information may also be used to warn the vehicle operatorof a potentially hazardous situation such as following the forwardvehicle too closely for the current vehicle speed or approaching theforward vehicle or another object too rapidly such that a collision mayoccur. An example of an advanced cruise control system is disclosed inU.S. Pat. No. 6,076,622 issued to Eaton VORAD Technologies, LLC.

[0005] Oftentimes the advanced cruise control systems and engine controlsystems are manufactured by different companies. It is thereforeimportant to have a standard communication format to permit thesedevices to communicate with various engine manufacturers' enginecontrollers. Standards, recommendations, guidelines, specifications, andthe like, hereinafter collectively referred to as standards, arecontinually developed and published by various organizations. Thesestandards designate component characteristics, testing procedures,communications formats, standards and methods of operation. Suchorganizations include the International Standards Organization (ISO),the Society of Automotive Engineers (SAE), and the Institute forElectrical and Electronics Engineers (IEEE), among numerous others.Often standards published by one organization will have correspondingdesignations in other organizations or may be a conglomeration ofvarious other standards. Standards of particular interest in providingelectronic engine control for vehicles such as heavy-duty tractorsemitrailer vehicles are published by the SAE, one of which isdesignated SAE J1939. As is known, ISO 11898 is generally similar to andcompatible with SAE J1939.

[0006] The J1939 standards define various control modes forelectronically controlled engines including a normal mode, a cruisecontrol mode, a torque control mode, and a speed and torque limitcontrol mode. In normal mode, engine fueling is controlled basedprimarily on input received from the vehicle operator, typically via athrottle pedal. Of course a number of other factors influence the actualdetermination of engine fueling as described in greater detail below. Ina standard cruise control mode, engine fueling is controlled to maintaina substantially constant engine speed. In torque control mode, asubstantially constant engine output torque (as a percentage of totalavailable torque) is effected regardless of engine speed and vehiclespeed. Speed and torque limit control mode imposes an upper limit onengine speed and/or engine output torque. The override modes may be usedto override the current operating mode and command the engine to aparticular engine speed or engine output torque. The control mode isbased on current operating conditions and commands received by theengine controller which may be generated by various other vehiclesystems and subsystems or by the vehicle operator. A more detaileddescription of the modes of operation may be found in the J1939specifications, the disclosures of which are hereby incorporated byreference in their entirety. Other, related standards utilized inelectronic engine control and communication include SAE J1587, SAEJ1708, and SAE J1843, the disclosures of which are also herebyincorporated by reference in their entirety.

[0007] As will be readily apparent to those skilled in the art, it isimportant for the engine controller to receive accurate data from theadvanced cruise control system so that the engine controller, andparticularly the cruise control, responds to vehicles or other detectedobstacles. Although the data bus communications standards set forth inJ1939 work satisfactorily, there are instances when too much data ornoise on the bus, among other reasons, prevents the engine controllerfrom receiving a particular data transmission, or causes the data to becorrupted. In prior art systems, the engine controller will simplydisable the advanced cruise control system once an invalid datacommunication signal is received and causes the system to remaindisabled until the engine controller has been re-initialized, whichgenerally requires that the operator turn the ignition switch off, thenre-start the engine. Although this system does help insure that theengine controller receives valid data from the advance cruise controlsystem, it is inconvenient for the operator to have to re-initialize thecontroller for every invalid data transmission. It would be preferableto have a control system that overcomes these and other disadvantagesassociated with the prior art.

SUMMARY OF THE INVENTION

[0008] In one aspect of the present invention, a compression ignitionengine includes an electronic controller that produces fuel deliverycommands to control power output of said engine. The electroniccontroller is connected with an advanced cruise control system. Theelectronic controller receives communication signals produced by theadvanced cruise control system, determines whether there has been acommunication fault and responsively affects operation of the advancedcruise control system.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009]FIG. 1 depicts a system level block diagram of an exemplary systemincorporating an embodiment of the present invention; and

[0010]FIG. 2 is an embodiment of software control used in connectionwith an embodiment of the present invention.

DETAILED DESCRIPTION

[0011] The following is a detailed description of the best modeembodiment of the present invention, with sufficient detail to permitsomeone skilled in the art to make and use the claimed invention. Thepresent invention, however, is not limited to the embodiment disclosedand described herein. To the contrary, the present invention may includeall those alternative embodiments and equivalents that fall within thescope of the present invention as defined by the appended claims.

[0012] Referring first to FIG. 1, a block diagram of a control system 10for use with a compression ignition engine 20 is shown. As shown in thedrawing, the compression ignition engine 20 preferably includes a fuelsystem 30 which in a preferred embodiment includes a fuel injectorassociated with each of the engine cylinders. Although the fuel systemof the preferred embodiment includes fuel injectors, alternativeembodiments may include a carburetor or other fuel delivery mechanism.The fuel system 30 is preferably electrically connected with anelectronic control module (“ECM”) 40 that delivers fuel deliverycommands to each of the fuel injectors thereby causing a commandedquantity of fuel to be injected into the cylinders at a commanded time.

[0013] The ECM 40 is preferably connected with a data bus 50, which in apreferred embodiment is governed by the Society of Automotive Engineers(SAE) standard J1939. Although the preferred embodiment utilizes a databus with the J1939 standard, other data bus standards could be used inother applications without deviating from the scope of the presentinvention. For example, in off-highway applications, particularly inmining equipment or the like, the data bus might comply with a differentstandard or might be a data bus specific to the manufacturer of theequipment. Included within the ECM 40 are software programs and hardwarenecessary to run the engine 20 and other programs to perform control ofvarious vehicle functions and accessories, including program control fora cruise control feature 41.

[0014] Various operator inputs 60 are preferably in electricalcommunication with the ECM 40 over the data bus 50. These operatorinputs are typical inputs for the particular application, which inon-highway trucks include inputs well known to those skilled in the artincluding a throttle input and cruise control inputs including anon/off/resume switch and a set switch. Other operator inputs may also beincluded.

[0015] Vehicle, engine and transmission sensors 70 are also preferablyconnected with the data bus 50 and are in electrical communication withthe ECM 40. Typically, these sensors may include an engine speed sensor,a vehicle speed sensor, a transmission gear sensor among other sensors.

[0016] Also connected with the data bus 50 is an advanced cruise controlsystem 80. These systems are well known in the art and are availablefrom several different manufactures. On such system is manufactured byEaton VORAD Technologies, and is known as EVT-300 with SMARTCRUISE®.Another example of such a system is disclosed in U.S. Pat. No. 6,076,622assigned to Eaton VORAD Technologies, L.L.C., the disclosure of which isincorporated herein by reference. Any one of these systems can be usedin connection with an embodiment of the present invention. As is knownto those skilled in the art, the advanced cruise control system 80communicates with the ECM 40 over the data bus 50 and preferablycommunicates data or instructions to the cruise control feature 41,which are then used to control fuel delivery to the engine 20, orcontrol command signals issued to a compression brake (not shown). In apreferred embodiment, the advanced cruise control system 80, produces aperiodic data output onto the data bus 50, which in a preferredembodiment occurs about every 100 ms. Those skilled in the art willrecognize that other periodic rates could readily and easily be used.Although the advanced cruise control system 80 of a preferred embodimentproduces periodic signals, in other embodiments different communicationsprotocols and formats may be used without deviating from the scope ofthe present invention as defined by the appended claims. For example,the communications may be interrupt driven, or have hand-shaking wherebythe ECM 40 prompts the advanced cruise control system 80 for data. Stillother protocols and formats are know to those skilled in the art andcould be used in connection with the present invention.

[0017] Referring now to FIG. 2, software control for an aspect of thedata communications employed in a preferred embodiment of the presentinvention is shown. Those skilled in the art will recognize that theflowchart of FIG. 2 is a description of one embodiment of computercontrol used in connection with the invention and that other flowcharts,with varying degrees of detail, could be used to describe the samesoftware program. Still other algorithms and computer programs could bedeveloped that perform the same or equivalent functions, but would berepresented by a different flowchart. The flowchart depicted in FIG. 2is therefore exemplary of an embodiment of the control used inconnection with an aspect of the present invention. Those skilled in theart could readily and easily write appropriate software control programsfrom the flowchart of FIG. 2 using the programming language associatedwith the specific microprocessor or microcontroller used in the ECM 40.

[0018] Program control begins in block 200 and passes to block 210. Inblock 210, program control resets a clock variable (CLK) to zero.Program control then passes to block 220.

[0019] In block 220, program control starts the variable CLK, whichthereafter keeps track of the elapsed time. In conjunction with block230 as described following, the variable CLK keeps track of the timeelapsed since a valid communications signal has been received from theadvanced cruise control system 80. Although the flowchart shows the CLKas being reset to zero each time program control passes through block210, in other embodiments, the current time reading of the system clockor other clock could be stored in the variable CLK in block 220, whichcould then be compared to the system clock to determine an amount ofelapsed time. Thus, the flowchart is meant to generically depict one ofany number of specific ways of determining an elapsed time.

[0020] In block 230, program control causes the ECM 40 to assess whethera communication signal is received from the advanced cruise controlsystem 80 over the data bus 50 and whether the communication signal is avalid signal. Those skilled in the art will recognize that there aremany different kinds of signal validation techniques for digitalcommunications such as those transmitted over the preferred data bus 50.Examples of such validation techniques could include checksum, CRC, MNPor CCITT V.42 among other techniques, any of which could be used toverify that the transmitted signal has not been compromised by noise onthe data bus 50, data collisions that may occur when two differentdevices attempt to transmit data on the bus at almost the same time, orother known causes of distorting the data. If the communication signalis received and is a valid signal, then program control returns to block210. As can be seen from the flowchart, so long as the communicationsignal is received and valid, program control for this subroutine of theoverall ECM 40 program control will continue to loop through blocks 210,220 and 230. Of course, those skilled in the art will recognize that themicroprocessor is continuing to perform other functions in between theperiods when various aspects to the present routine are being performed.In block 230, if the communication signal is not received or is invalid,then program control passes to block 240.

[0021] In block 240, program control causes the elapsed time stored inthe variable CLK to be compared with a predetermined value stored in avariable t1. In a preferred embodiment t1 is 500 ms, although othervalues could readily and easily be used. If the CLK value is less thanthe value t1, then program control passes to block 250, otherwiseprogram control passes to block 260.

[0022] In block 250, the status of the advanced cruise control system 80remains unchanged. That is, if the advanced cruise control system 80 wasengaged, then so long as the CLK value is less than the value stored int1 the advanced cruise control system will remain engaged. Thus, if theECM 40 receives only a single invalid communication signal (or severalinvalid communication signals so long as the total number do not exceedthe time period t1), a preferred embodiment of the invention will notdisable the advanced cruise control system. Program control passes fromblock 250 to block 230, where the ECM 40 again determines whether thereis a valid communication signal.

[0023] Returning to block 240, if the CLK value is greater than tl, thenprogram control passes to block 260. In block 260, program controlcompares the CLK variable to a second value t2. In a preferredembodiment, t2 is approximately 3500 ms, although other values couldreadily and easily be used in other embodiments or systems. If no validcommunication signal has been received while the CLK value is greaterthan t1, but less than or equal to t2, then program control passes toblock 270 and the ECM 40 disengages the advanced cruise control feature.The term disengaged is used here to mean that the advanced cruisecontrol no longer actively controls fuel delivery nor does it controlactivation of the compression brake. The operator can re-engage theadvanced cruise control without having to re-initializing the ECM 40,(which would require for example stopping the truck, turning off theengine 20 and restarting the engine 20). Instead, to re-engage theadvanced cruise control feature, the operator will manipulate at leastone of the operator inputs; in a preferred embodiment the operator willpress one of the set or resume cruise control inputs. If, in block 260,the CLK value exceeds the second value t2, then program control passesto block 280.

[0024] In block 280, the ECM disables the advanced cruise controlfeature because the absence of a valid signal between the advancedcruise control system 80 and the ECM 40 generally indicates that thereis a communication failure or a serious defect in the communicationsbetween those devices. In a preferred embodiment, the operator will berequired to re-initialize the ECM 40, preferably by stopping the truck,turning off the engine 20 and restarting the engine 20. Also in apreferred embodiment, if the operator manipulates the cruise controlinputs once the ECM 40 has disabled the advanced cruise control system80, the ECM 40 will cause the cruise control feature 41 to control theengine without using the advanced features of the system 80.

INDUSTRIAL APPLICABILITY

[0025] In an embodiment of the present invention, an ECM 40 is inelectrical communication with an advanced cruise control system 80 overa data bus 50. The advanced cruise control system 80 preferably includesa radar or other distance sensing device that senses the presence ofvehicles or other objects in front of the truck and the distance thatthose vehicles or objects are in front of the truck. The advanced cruisecontrol system also includes control and communication circuitry tocalculate the closing rate between the truck and the vehicle andcommunicate that information in communication signals to the ECM 40.

[0026] By using an embodiment of the present invention, the ECM 40 willallow the advanced cruise control to continue operating forcommunication errors less than the time t1. Thus, a single isolatedcommunication error will not cause the system to disengage or bedisabled. If the communication error continues for a time greater thatt1 but less than t2, then the ECM 40 recognizes a communication errorand disengages the advanced cruise control system 80. If thecommunication error continues for a time greater than t2, then acommunication failure likely exists, for example a bad connectionbetween components or faulty wiring, and the ECM 40 disables theadvanced cruise control system 80.

What is claimed is:
 1. A compression ignition engine, comprising: anelectronic controller, said electronic controller producing fueldelivery commands to control power output of said engine, saidelectronic controller including a cruise control mode; an advancedcruise control system connected with said electronic controller andproducing communication signals; wherein said electronic controllerreceives said communication signals and calculates a fuel deliverycommand based, at least in part, on said communication signals at leastwhen said electronic controller is in an advanced cruise control mode;and wherein said electronic controller disengages said advance cruisecontrol mode in response to receiving no valid control signal forgreater than a first period of time.
 2. The compression ignition engineof claim 1, wherein said electronic controller disables said advancecruise control mode in response to receiving no valid control signalsfor greater than a second period of time.
 3. The compression ignitionengine of claim 1, wherein said first period of time is less than about500 milliseconds.
 4. The compression ignition engine of claim 2, whereinsaid second period of time is less than about 3500 milliseconds.
 5. Thecompression ignition engine of claim 1, wherein said first period oftime is about 500 milliseconds.
 6. The compression ignition engine ofclaim 2, wherein said second period of time is about 3500 milliseconds.7. The compression ignition engine of claim 1, wherein said electroniccontroller re-engages said advanced cruise control system in response tooperator cruise control inputs.
 8. The compression ignition engine ofclaim 7, wherein said operator cruise control inputs include on of acruise control resume switch and a set switches.
 9. The compressionignition engine of claim 2, wherein said electronic controllerre-enables said advanced cruise control in response to operatorre-initialization of the electronic controller.
 10. The compressionignition engine of claim 9, wherein said operator re-initializationincludes turning off the engine and turning it back on.
 11. A method ofcontrolling a compression ignition engine equipped with an electroniccontroller and an advanced cruise control system, said methodcomprising: receiving communication signals from said advanced cruisecontrol system; and disengaging said advanced cruise control system as afunction of not receiving valid control signals for a first time period.12. The method of claim 11, further comprising: disabling said advancedcruise control system as a function of not receiving valid controlsignals for a second period of time.
 13. The method of claim 11, furthercomprising: re-engaging said advanced cruise control after said step ofdisengaging, in response to operator cruise control inputs.
 14. Themethod of claim 12, further comprising: re-enabling said advanced cruisecontrol in response to said operator turning off the engine and turningit back on.
 15. The method of claim 13, wherein said operator cruisecontrol inputs include an cruise control resume switch.
 16. The methodof claim 11, further comprising: engaging cruise control, after saidstep of disabling, in response to operator cruise control inputs.